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chumicro-kvstore

A persistent dict for counters, timestamps, and tokens that need to survive a reboot.

A dict-shaped store with commit() semantics. Auto-detects the right backend per runtime (NVM on CircuitPython, NVS on ESP32 MicroPython, LittleFS elsewhere, in-memory for tests), bounds writes with commit_if_changed() so unchanged state doesn't wear the flash, and surfaces capacity and corruption honestly.


Part of the ChuMicro family: small, focused Python libraries for microcontrollers and laptops. Browse all libraries.

Install

# CircuitPython (after `circup bundle-add ChuMicro/ChuMicro-Bundle`)
circup install chumicro_kvstore

# MicroPython
mpremote mip install github:ChuMicro/ChuMicro-Bundle/chumicro_kvstore

# CPython
pip install chumicro-kvstore

For bundle setup, pre-compiled .mpy bundles, the experimental channel, and details on PyPI naming, see the chumicro INSTALL guide.

Quick example

Boot counter that survives reboot:

from chumicro_kvstore import KVStore

store = KVStore(backend="auto")
store["boot_count"] = store.get("boot_count", 0) + 1
store.commit_if_changed()              # no flash write if value unchanged
print(store["boot_count"])             # → 1, 2, 3, … across power cycles

What's included

Symbol What it does
KVStore(backend="auto") Mapping-shaped store; auto-detect picks NVM (CP), NVS (MP-ESP32), LittleFS (MP non-NVS), or memory (CPython)
store[key] / store[key] = v / del store[key] Standard dict semantics
store.commit() Encode + persist current state
store.commit_if_changed() Skip write when payload is unchanged (wear defense)
store.reload() Discard in-memory state, reread from backend
store.capacity / bytes_used / is_corrupt / backend_name Honest substrate introspection
KVStoreFull / KVStoreCorrupt Targeted exceptions (catch KVStoreError for both)
chumicro_kvstore.testing.FakeKVStore Drop-in for downstream tests with capacity + corruption hooks

Where this fits

Leaf, with no upstream ChuMicro deps. Used directly in app code; no other ChuMicro library depends on it.

Platform support

Works on CPython, MicroPython, and CircuitPython.

Examples

Example What it shows
boot_counter.py Boot counter persisted across reboots; auto-detect picks the right backend per runtime

Contributing

Issues, bug reports, and pull requests are welcome, and so is "I ran it on this board and here's what happened", some of the most useful feedback a hardware project can get. Development happens in the ChuMicro repository, whose contributing guide covers setup and the test workflow.

Docs

📖 Stable docs · Experimental docs

Find this library

License

MIT

Release files for chumicro-kvstore 0.3.5

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0.3.6

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0.3.2

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0.3.1

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